code: def test_compute_diff(self):
      self.assertEqual(
          cross.compute_diff([1, 1, 1], [0, 1, 2]), [1, 0, -1]
      )
      self.assertEqual(
          cross.compute_diff([0, 1, 2], [1, 1, 1]), [-1, 0, 1]
      )
  
file_path: pyalgotrade/testcases/technical_cross_test.py
imports: from .None import common
  from pyalgotrade.technical import cross
  from pyalgotrade.technical import ma
  from pyalgotrade import dataseries
label_desc: Use image node_id 3 for calling the HelpersTestCase obj's underlying member method code with example usage: obj.test_compute_diff() without return types